Disclosed herein is a vehicle seat, and particularly, a vehicle seat that includes an elevation mechanism adjusting the height of a seat cushion and a brake mechanism maintaining the height of a seat cushion when the elevation mechanism is not driven.
Among vehicle seats, a vehicle seat including a mechanism adjusting the position or the posture of a seat body is known, and an elevation mechanism adjusting the height of the seat body is exemplified as an example of the adjustment mechanism (for example, see Japanese Patent Document 2011-246024 A (“the '024 Document”)). The elevation mechanism is generally disposed below a seat cushion, and is driven in a manner such that an occupant sitting on a vehicle seat manipulates a manipulation member such as a manipulation lever.
Further, the vehicle seat disclosed in “the '024 Document” includes a brake mechanism that maintains the height of the seat body when the elevation mechanism is not driven. Since the brake mechanism prevents a driving portion (for example, a pinion gear or the like) of the elevation mechanism from being driven unintentionally, the movement of the driving member is limited by a friction force or the like. In general, the brake mechanism is attached to the seat cushion, that is, a cushion frame constituting a framework of the seat cushion.
If a load generated by a rear collision or the like is applied to the vehicle seat in the front to back direction when the vehicle equipped with the vehicle seat travels, the load is first applied to a seat back of the vehicle seat. Subsequently, the load (hereinafter, also referred to as the input load) applied to the seat back is transmitted to the cushion frame of the seat cushion connected to a seat back frame. In a configuration in which a member like the above-described brake mechanism or the seat back frame is attached to the cushion frame, the rigidity of a portion other than the attachment portions of the other members in the cushion frame decreases inevitably. In the case of a seat structure in which a load transmitted from the seat back frame is continuously applied to such low-rigid portions, it is difficult to mention that this seat structure is desirable from the viewpoint of the strength of the cushion frame. For this reason, there is a need to improve the rigidity of the low-rigid portions of the cushion frame. Thus, a method is considered which further increases the size of the cushion frame in the width direction by further thickening the thicknesses of the low-rigid portions. However, in the above-described method, as a countermeasure, there is a possibility that the cushion frame may be increased in weight or size.
Further, when the seat back falls forward or backward by the load input to the seat back, a compression force and an extension force are simultaneously generated in the front to back direction near the connection portion with respect to the seat back frame in the cushion frame. For this reason, there is a need to improve the rigidity of the cushion frame with respect to these forces.
Further, when the cushion frame is equipped with a support shaft for supporting the other member or a rotary shaft for rotating the other member, the shaft needs to be supported stably. Particularly, when a plurality of shafts are attached to the cushion frame, the distance between the shafts needs to be maintained.
Further, when the rigidity of the portion without the other member like the brake mechanism in the cushion frame is improved, it is also desirable to improve the rigidity of the peripheral portion thereof. Similarly, it is desirable to improve the rigidity of the portion without the other member like the brake mechanism in the cushion frame and to improve the rigidity of the portion with the other member.
Further, there is a case in which the elevation mechanism includes a gear such as a sector gear as the component thereof. Here, when the gear is disposed near the cushion frame, there is a need to suppress an increase in size of the cushion frame while avoiding the interference with the gear.